The present invention relates to a method and apparatus for monitoring and adjusting a laser welding process, and more particularly, a method and apparatus having a closed looped system within a laser material processing head for monitoring and adjusting a laser welding process.
In most industrial laser welding processes, a two-dimensional or three-dimensional workpiece may be welded, cut or otherwise processed. The devices which perform the laser welding may be programmable, thereby allowing the contour of a weld seam to be pre-programmed according to ideal workpiece dimensions and positions. However, as the laser welding device follows the pre-programmed contour of the weld seam, the laser welding device does not consider the deviations which occur between the ideal positioning and dimensioning of the workpiece and the actual position and dimensional measurements of the workpiece. Deviations from the theoretical positioning and dimensioning of the workpiece are introduced through the limits and accuracy of handling systems, tolerances in the dimensions of the workpiece, and tolerances in the fixturing of the workpiece.
The cost of trying to reduce or eliminate the tolerances involved in the dimensioning and positioning of the workpiece is significant, if not cost prohibitive. Such deviations in the tolerances of the workpiece may be compensated for by altering the position of the laser beam. Previous systems have utilized sensors that measure the offset between the actual position of the laser beam and a predetermined targeted position. A signal from a sensor is sent to a controller of a handling system wherein the relative position between the laser beam and the workpiece is adjusted. However, communication between the sensor and the appropriate controller of the handling systems is cumbersome and difficult in that no standardized interfaces exist between the sensors incorporated in a laser beam head and a controller of a handling system. Thus, when the laser beam head is removed from the handling system and replaced with another handling system, or vice versa, the interface between the laser weld head and the handling system must be reconfigured and re-engineered. In a commercial environment, this is an ineffecient and expensive process.
It is desirable to create a laser material processing head that incorporates a closed loop monitoring system within the laser material processing head for providing the necessary adjustments to a laser welding process.
The present invention is a method and apparatus for monitoring and adjusting a laser welding process. A laser material processing head provides a laser source that provides a laser beam for laser welding a workpiece. A position sensor, coupled to the laser material processing head, measures the difference between the actual position of the workpiece and a predetermined theoretical position of the workpiece. An adjusting means, disposed within the head, positions the laser beam in response to a signal from the position sensor. A closed loop controller, coupled to the laser material processing head, interfaces the position sensor with the adjusting means to allow the adjusting means to properly position the laser beam with respect to the workpiece. A process sensor, coupled to the laser material processing head, may also be provided for indicating the quality of the weld created by the laser welding process. The closed loop controller may interface the process sensor with the adjusting means to properly adjust the laser beam by adjusting the power level of the laser source. The process sensor may also communicate with the handling system, separate from the laser material processing head, for adjusting the position of the workpiece relative to the laser head.
The adjusting means may provide a means for reflecting the laser beam toward the workpiece. The reflecting means may provide at least one mirror mounted on at least one pivotal axis. In addition, the mirror may also provide a concave surface for reflecting the laser beam.
The adjusting means may also provide a transparent means for redirecting the laser beam toward the workpiece. The transparent means may provide at least one prism mounted on a pivotal axis for pivoting the prism about at least one axis. The transparent means may also provide substantially flat parallel glass plates for deflecting the laser beam toward the workpiece.
Lastly, the adjusting means may provide an optic lens for focusing the laser beam onto the workpiece.